Auxiliary evaporator for dual mode heat pipes

Abstract

A dual mode heat pipe includes roadways, bridges, etc., includes an auxiliary evaporator formed concentrically with the upper end of a vertically disposed primary evaporator portion. The auxiliary evaporator portion comprises an annular sleeve disposed about the upper end of the primary evaporator portion and arranged between the primary evaporator portion and the condenser portion of the heat pipe such that all of the condensed working fluid returning to the primary evaporator portion must enter and overflow the auxiliary evaporator portion prior to return to the primary evaporator portion. The auxiliary evaporator portion is provided with heat input means whereby the auxiliary evaporator may function even in the absence of heat pipe function by the primary evaporator.

What is claimed as new is as follows: 
     
       1. Heat pipe apparatus comprising means containing a condensable working fluid and having a vertically disposed energy input portion and an energy output portion, the energy output portion including a condenser portion in which the working fluid condenses to release heat, the condensed working fluid returning to the energy input portion for vaporization by energy applied to the input portion externally thereof, the energy input portion comprising: primary evaporator means comprising a tubular member sealed at one end and open at its other end for containing at least a portion of the working fluid, at least a portion of the working fluid being vaporized therein; and   auxiliary evaporator means comprising a tubular sleeve disposed in concentrically spaced relationship about the open end of the tubular member, said tubular sleeve having a closed end portion sealed to the outer wall surfaces of the tubular member whereby a condensate receiving space is defined between the inner wall surfaces of the tubular sleeve and the outer wall surfaces of the tubular member, and the other end of said tubular sleeve extending upwardly of the open end of the tubular member and being in communication with said condenser portion for containing a portion of the working fluid and being disposed between the condenser portion and the primary evaporator means, said auxiliary evaporator means being so constructed and so arranged relative to said primary evaporator means that all of the condensed working fluid returning to the energy input portion enters the auxiliary evaporator means prior to return of a portion thereof to the primary evaporator means, said auxiliary evaporator including a heat producing means for supplying heat thereto.   
     
     
       2. The heat pipe apparatus of claim 1 wherein the tubular sleeve is extended to define the condenser portion of the energy output portion. 
     
     
       3. The heat pipe apparatus of claim 2 wherein the portion of the tubular sleeve defining the condenser portion of the energy output portion is disposed relatively above that portion of the tubular sleeve defining the auxiliary evaporator means. 
     
     
       4. The heat pipe apparatus of claim 1 and further comprising wick means formed on the inner walls of the tubular sleeve surrounding the tubular member for transport of the working fluid within the auxiliary evaporator means. 
     
     
       5. The heat pipe apparatus of claim 4 and further comprising second wick means formed on the outer surface of the end of the tubular member surrounded by the tubular sleeve for transport of the working fluid within the auxiliary evaporator portion. 
     
     
       6. The heat pipe apparatus of claim 5 and further comprising a helical coil formed of capillary material disposed within the space between the tubular sleeve and the end of the tubular member surrounded by the tubular sleeve. 
     
     
       7. The heat pipe apparatus of claim 1 wherein said heat producing means for said auxiliary evaporator means is disposed about the external wall surfaces of the tubular sleeve. 
     
     
       8. The heat pipe apparatus of claim 7 and further comprising thermal insulation means for enclosing the tubular sleeve and the heat producing means.